With decreasing reserves of light crude oil we have been led to extract lower quality crudes (sour crudes) which are high in sulphur and metals. The costs associated with de-contaminating, or elevating this crude to International fuel standards is much higher, requiring in some cases the purchase of lighter crudes to reduce contaminants in general due to a lack of cost effective technologies to completely eliminate or significantly reduce these contaminants. The petroleum industry is always looking for more economical ways to crack, distil, refine and improve on fuel characteristics. Recent environmental requirements for fuels to exceed EPA standards, and having the rest of the World focusing on the reduction of these contaminants as well, have prompted the industry to explore new methods to reduce these non-desired elements or substances in the least expensive manner.
The conventional process used in the petroleum industry for Sulphur reduction is known as hydrolysis. The hydrocarbon is reacted in one or more vessels, incorporating a hydrolysis catalyst and an absorption stage to trap the reacted sulphur. This occurs under high temperature and pressure conditions with sophisticated equipment and requires extensive footprint and energy resources.
Also, hydrocracking is a process used in the oil industry to convert low quality raw materials into higher-value fuel. This process is the best way to obtain a diesel fuel with lower sulphur content and aromatics. Normally the hydrocracking process is carried out using two suspended bed catalytic packed reactors that operate at high pressure and temperature. In the first reactor the molecule is ruptured, releasing sulfur and nitrogen, then the liquid fraction enters the second reactor where it is hydroisomerized and cracked. The hydrocracking process allows a variety of liquid fuels with certain undesirable characteristics to conform to existing environmental requirements.
These conventional processes have a high demand in energy and require large spaces for the process to take place, aside from the use of catalysts and other consumables which require periodical exchange or replacement. All this represents an added cost for the industry, especially now that we have to work with heavier fractions of sour crude oil.